Patent Application
20060079750
The present invention relates to a system and method using dynamic infrared imaging for localizing vascular architecture, and for evaluating and monitoring functional behavior of the vascular architecture for pre-operative, post-operative, and diagnostic purposes.
The concept of infrared imaging for biomedical applications has been explored for some time. The early technology used, unfortunately, had neither the sensitivity, resolution nor speed to be of substantial value. Infrared imaging has now advanced to where it is being used for a range of applications in medicine, and has multiple advantages over conventional medical imaging techniques, including, low cost, no ionizing radiation and minimal need for contrasting agents. The existing infrared systems, however, are limited in sensitivity and speed. As such, the use of these systems for identifying, for instance, vessel architecture, can be crude and can require the use of contrast enhancement techniques, such as cooling the area of interest or the use of contrast agents.
Moreover, existing medical imaging systems are limited to collecting information about the tissue physiology in a single band (i.e., wavelength spectrum) of emission. In addition, since these systems typically use static measurements of spatial distribution of photon flux, they may display only information pertaining to, for example, the infrared flux at a particular single band, rather than information in multiple infrared bands or dynamics of infrared photon flux over time. Due to the nature of infrared energy, namely the absorption of specific bands of infrared photons by certain components of biological tissue, such as gasses and fluids, there would be significant advantages in employing a multiband detector that could analyze and display multiple bands of infrared energy simultaneously. A properly designed system would permit the direct analysis of gas, fluid and other diagnostically important tissue characteristics.
With certain surgical procedures, such as reconstructive surgery where free tissue transfer may be involved, there can arise problems that prevent a successful outcome of such a procedure. Specifically, the ability to precisely identify the vascular pedicle, the ability to identify the perforator vessels that perfuse the selected free tissue flap, as well as the performance of a vascular anastomosis with the recipient vessels, can determine whether there will be a successful outcome.
Currently, there are commercially available systems that permit the objective localization of the vascular architecture, such as the perforator vessels. These systems, however, do not typically employ infrared imaging. Rather, one approach is to use, for instance, ultrasound Flow Doppler Meter. However, such an approach can be time consuming and may not yield accurate results. Moreover, the use of thermal imaging to localize cutaneous perforators has been discussed in the literature. However, such an approach focuses on temperature variations and requires the application of a cold stimulus (fan cooling, ice packs, etc.) prior to imaging, which can be uncomfortable to a patient, or a contrasting agent, which can generate adverse effects in a patient when delivered within the patient's body and/or when a high level of energy is used. Furthermore, during a pre-operative period, currently available systems may not be able to allow a healthcare provider to accurately evaluate the vascular architecture. Similarly, during a pre-operative or post-operative period, these systems may not allow the provider to essentially instantly evaluate blood perfusion activity in the area of interest, so as to avoid the potential damage or loss of existing or transplanted tissue.
Accordingly, it would be advantageous to provide a system and method that can provide a fast, reliable, accurate, non-invasive approach to the objective localization of vascular architecture to facilitate the evaluation and monitoring of functional behavior of the vascular architecture for pre-operative, post-operative and diagnostic purposes.
The present invention provides, in one embodiment, a dynamic imaging system having a scanner designed to include a body portion and an objective portion. The system also includes an assembly, positioned within the objective portion, for splitting a photon beam emitted from an object being monitored into multiple incident rays of different wavelength spectra. The system also includes a detection network designed to receive the multiple incident rays for converting, into electronic signals, data correlated from the respective incident rays. The detection network, in an embodiment, may include an infrared detector. Such a detector may be a quantum well infrared photodetector (QWIP). The system may further include a processor for generating discrete image data from the electronic signals of each respective incident ray. The image data regarding the object being monitored may subsequently be viewed on a display. The system can also include at least one ruler for positioning on the object being monitored to permit subsequent translation of the image viewed in the display onto the object.
The present invention provides in another embodiment, a dynamic imaging system having, among other things, an objective portion through which a photon beam emitted from an object being monitored may be directed. The system, in an embodiment, may include a plurality of mirrors within the objective portion for splitting the photon beam into multiple incident rays, each of a different wavelength spectrum. At least one detector may be provided and tuned to a specific wavelength spectrum of the incident ray it is collecting from the corresponding mirror, so as to convert, into electronic signals, data correlated from the incident ray. The system further includes a processor for generating discrete image data from the electronic signals of each respective incident ray. The image data in connection with the object may subsequently be viewed on a display. The system can also include at least one ruler for positioning on the object being monitored to permit subsequent translation of the image viewed in the display onto the object.
In another embodiment, the present invention provides a method for evaluating vascular architecture of a tissue area on a patient. The method includes initially maintaining, at substantially normal body temperature, the tissue area having the vascular architecture of interest on the patient. Next, photon flux emitted from the tissue area may be detected. In one embodiment, a stream of individual frames of data from detected photon flux may be collected. Thereafter, data collected from the detected photon flux may be processed. Subsequently, contrast between the vascular architecture and surrounding tissue within the area being scanned may be enhanced, and an image from the processed data may be displayed for viewing. In accordance with an embodiment of the invention, the image displayed may be used for pre-operative and/or post-operative evaluation.
In further embodiment, a method for localizing perforator vessels is provided. The method includes initially maintaining, at substantially normal body temperature, the tissue area having the vascular architecture of interest on the patient. Next, a reference point may be placed on the tissue area to assist in subsequent localization. Thereafter, the tissue area may be scanned with an infrared camera, so that the reference point is within the field of scan to detect photon flux emitted from the tissue area. In one embodiment, the reference point may be provided by placing a ruler having calibrated markings onto the tissue area. Then, data collected from the detected photon flux may be processed. Subsequently, contrast between the vascular architecture and surrounding tissue within the area being scanned may be enhanced, and an image from the processed data may be displayed for viewing. An electronic illustration of a grid having a coordinate system may next be positioned on the image displaying the perforator vessels, such that the origin of the grid is situated relative to the reference point captured during the scan. Then, the location of the perforator vessels within the grid may be identified. Thereafter, while maintaining orientation of the grid relative to reference point, the location of the perforator vessels within the grid may be translated to the tissue area previously scanned. Subsequently, the location of the perforator vessels as identified within grid may be marked on the tissue area.
FIGS. 9A-B illustrate a various embodiments for a light source for use in connection with the dynamic imaging system of the present invention.
The present invention, in one embodiment, is directed to a system and method for localizing vascular architecture, and for the evaluation and monitoring of the functional behavior of the vascular architecture for pre-operative, post-operative and diagnostic purposes. The system employs a detection network of at least one detector, single or multiple bands, that is capable of collecting photons of various wavelengths for dynamic imaging of a tissue area of interest. The dynamic imaging system of the present invention may also permit a user to view multiple bands of electromagnetic radiation concurrently as individual images or as a merged or superimposed image.
With reference now to
In another embodiment, looking now at
As the body portion 21 and the objective portion 22 are designed to house the working components of the scanner 20, these portions, in one embodiment, may be made from a strong material, such as, a metal, a metal alloy, molded plastic, fiberglass, or a combination thereof. In addition, although illustrated in
Referring now to
Although only two mirrors are illustrated in
In an alternate embodiment, assembly 31 may include, instead of an array of mirrors, a plurality of filters, shutters, hot/cold prisms, or a combination thereof, each similarly capable of separating and/or reflecting photons within a specific wavelength spectrum while being transparent to photons within other wavelength spectra. Furthermore, to the extent necessary, these mirrors, filters, shutters, and/or hot/cold prisms may be fixed or made to be adjustable in order to vary the angle of incidence.
Still referring to
To collect the respective incident rays reflecting off of mirrors 33 and 34, a substantially clear pathway may be provided between the mirrors and detectors 35 and 36. In particular, an opening (not shown) may be provided at a juncture between the body portion 21 and the objective portion 22 that is sufficiently large to permit the incident rays 321 and 322 to move substantially unobstructively therethrough. In one embodiment of the invention, optics components, such as lens 351 and 361 may each be positioned upstream of detectors 35 and 36 respectively to permit the corresponding incident ray to be focused onto the respective detector. In addition, in accordance with an embodiment of the present invention, detectors 35 and 36 may be situated in such a manner so as to allow incident rays 321 and 322 to arrive at the respective detectors substantially perpendicularly to the surface of the detectors. To accommodate this, mirrors 33 and 34 may be fixed at an appropriate angle relative to the detectors 35 and 36, or may be adjustable to vary the angle of incidence.
In general, detectors 35 and 36 may be designed to correlate functional, physical and/or optical data from incident rays 321 and 322 coming from the same spatial and temporal source, i.e., object 24. It should be noted that since the correlated data came from photon beam 32 for all wavelength frequencies, any distortion that might be derived from the beams transmitted at different angles from object 24 may be minimized. In addition to correlating data, detectors 35 and 36 may be designed to convert the correlated data from the respective incident rays 321 and 322 into electronic signals.
It should be appreciated that although
Looking again at
The processor 37 may also be designed to implement various additional applications, for instance, (a) Pattern Recognition, (b) Dimensional Calibration Application, to assist in the calibration of an image that is being captured, (c) Grid Application, in which a grid with coordinates may be overlaid on the captured image to permit manipulation or modification of the image for subsequent activities, and (d) Measurement Application, for measuring the distances of the image for subsequent transfer of the tissue onto the body of the patient.
In one embodiment of the present invention, processor 37 may be positioned internally within the body portion 21 of the scanner 20, as illustrated in
Alternatively, processor 37 may be positioned externally of the body portion 21 and remotely from scanner 20. Although described in connection with the scanner 20, processor 37 can be used in connection with scanner 11. Scanner 11, as illustrated in
To permit visualization of the image signals generated by the processor 37, the scanner of the present invention may be provided with a display system, such as screen 14 on cart 15 in
Looking now to 5, in one embodiment of the present invention, the dynamic imaging system 10 may be equipped with lens system 50 for generating, among other things, infrared images of the object being monitored and observed. The lens system 50 may include a an infrared lens 51 for positioning over an object being monitored to collect photon flux emitted therefrom. This single lens system 50 may be used in connection with scanner 11 or scanner 20 of the dynamic imaging system 10.
In an alternate embodiment, looking now at
It should be noted that although the lenses 61, 62 and 63 are illustrated as separate confocal lenses, each with the ability to focus on a similar focal point concurrently as the others, these lenses may not necessarily be separate or discrete in design. Instead, they may be configured to be integral with one another. In addition, fewer or more than three lenses may be used. Regardless of the configuration or design, and depending on the imaging application, the lens system 60 may be made to collect photon beams within various other wavelength regions of the electromagnetic spectrum, e.g., x-rays, ultraviolet, etc.
The lens system 60, as illustrated in
The lens system 60, when positioned over object 64, may collect photon beams through each of the center lens 61 and side lenses 62 and 63. These beams, in accordance with an embodiment, may be directed as incident rays to three separate detectors similar to those detectors in
In accordance with one embodiment of the present invention, the lens systems 50 and 60 may be employed without the utilization of a beam splitting assembly, for example, assembly 31 in
The lens systems 50 and 60 may also be equipped with a focus or zoom component. In this manner, a user may be able to, among other things, view functional and optical images of small regions of interest with greater control, including the ability to control the presentation of the field of view, to study the subject tissue at normal and at magnified settings, to obtain a substantially clear and focused image at varying magnification or distance, and to obtain a field of depth which can facilitate eye hand coordination, while performing the surgical procedure. It should be appreciated that the use of multiple discrete lenses in lens system 60 can minimize issues typically associated with image degradation when approaching from a single lens solution.
In another embodiment of the present invention, the lens systems 50 and 60 of dynamic imaging system 10 may be equipped with one or more light sources for illuminating the object being monitored and viewed. As illustrated in FIGS. 9A-B, light source 90 may be situated, in one embodiment, about the opening 91 of the objective portion 22. In an embodiment whereby lens system 60 may be used, light source 90 may be situated about center lens 92 and/or side lenses 93 and 94. Light source 90, in accordance with one embodiment, may be a fiber optic light source, or any source which may generate diffuse illumination at the appropriate frequency on to the object being monitored and observed. The presence of light source 90, in one embodiment, can enhance the quality of the image data either by providing additional illumination and/or through spectral analysis, fluorescence or other means.
The dynamic imaging system 10 of the present invention further includes, in one embodiment, at least one ruler 100, such as that illustrated in
Referring again to
The dynamic imaging system 10 of the present invention may be adapted for a variety of uses. In one embodiment, the dynamic imaging system 10 can be used to obtain relatively fast and accurate images of the tissue area being evaluated and/or monitored. Moreover, since the imaging protocol employed by the system 10 can be based on the registration of passively emitted infrared photon flux from the tissue, the system 10 requires essentially no physical contact with the tissue or organ being evaluated and/or monitored.
Furthermore, the dynamic imaging system 10, can avoid using traditional contrast enhancement techniques, such as cooling the tissue area of interest or the use of contrast agents. By utilizing various algorithms which, among other things, can enhance the contrast between the vascular architecture and surrounding tissue, the system 10 can permit localization of the vascular architecture, while eliminating the need for cooling down the tissue area being observed (i.e., tissue area can be maintained at body temperature) and/or the need for using and delivering contrasting agents into the tissue.
In addition, the dynamic system 10 of the present invention can be used in a non-invasive manner to monitor, for instance, the physiological, functional, and/or structural characteristics of the tissue or organ being observed by analyzing the infrared energy that is emitted, absorbed or reflected from the tissue or organ. Specifically, a multi-spectral detector or multiple detectors may be used to collect, for example, infrared data from two or more bands and the intensity of each of the bands thereafter may be compared to determine tissue characteristics.
In particular, infrared photons, or “black body radiation”, emitted from the tissue and organ being monitored and observed may be collected as a stream of individual frames by the multi-spectral detector without the need to cool down the tissue. Subsequently, each frame may be analyzed and compared for changes in the photon flux. Changes in photon flux are typically the direct results of changes in tissue physiology. In one example, the multi-spectral system 10 may be used to identify/determine, among other things, an area of low blood flow in, for example, tissue graft, by comparing the intensity of the infrared flux at the absorption band of C02, about 3 to 5 μm, versus the absorption band of oxygenated hemoglobin, from about 0.1 to 2 μm, and preferably about 0.6 μm to 1.0 μm, or to any other band. This information could assist a surgeon in locating the optimal point for harvesting a graft.
Moreover, as there can be many biomedical applications which may require the ability to determine the concentration of naturally occurring or introduced chemicals in living tissue, the dynamic system 10 of the present invention may be used to measure, for instance, oxygen and/or C02 concentration to assist clinicians in assessing disease state and response to therapy. The ability to detect and measure, in vivo and in real time, concentrations of naturally occuring or introduced chemicals or gases in tissue or organs permit, in one embodiment, segmentations of data as a function of depth in tissue by comparing at least two frequencies that have different depth penetration capabilities, for example, about 3-5 μm vs. about 8-10 μm. The multi-spectral system 10 of the present invention, as should be noted, can be adapted to generate 3-D infrared data sets, which can further enhance this ability. In addition, detectors, including multi-spectral detectors, can be customized to track specific pharmacological substance introduced into tissue or be tuned to certain chemical by-products of disease, such as cancerous production of NO.
The dynamic imaging system 10 may also be used in pre-operative evaluation, for example, in the evaluation of the vascular architecture and more specifically, the perforator vessels. The ability to evaluate the vascular architecture can assist in the subsequent harvesting of a tissue flap, the assessment of the effects of diseases, such as cancer and diabetes, and the evaluation of vascular functional behavior using DAT, including non-infrared methods capable of monitoring changes in perfusion periodicity.
To perform a pre-operative evaluation of the vascular architecture prior to, for example, harvesting a tissue flap, in one embodiment, the objective portion on the scanner (e.g., scanner 11 or 20) of system 10 may be placed adjacent the area being evaluated, for instance, in front of a body part of a patient. It should be noted that the area being evaluated need not be cooled down and may be maintained at substantially normal body temperature when employing the system 10 of the present invention. Ruler 100, such as that shown in
Once the mark has been made, the dynamic imaging system 10 may be activated to permit the scanner to scan the area being evaluated. The scan, in one embodiment, may be about 20 seconds in length, but can vary in length of time, depending on the procedure. The system 10 may then process the data captured from the scan using, for example, one or a combination of the following algorithms: Spot FFT (Fast Fourier Transformation), Spot Standard Deviation, Spot Average.
The algorithms being employed with the system 10 may be applied to a collection of pixels called spots. In an example, a spot of size 1 represents one pixel, whereas a spot of size 2 represents collection of four adjacent pixels, and a spot of size 3 represents an area of 3×3 pixels—a collection of nine adjacent pixels. The average value of intensity of thermal photon flux may be calculated for the spot.
In connection with the evaluation protocol employed by the dynamic imaging system 10 of the present invention, Spot Average may be used to localize spots of increased temperature specific to the locations of perforator vessels. Spot Average includes the calculation of the average temperature value for the pixels included in the spot. Spot average temperature, once calculated, may be displayed in a form of a data matrix (frame). The values of the spot average temperature may be displayed in a gray scale mode or may be color coded according to a pseudo color palette. Spot average temperature matrices represent temperature distribution over the field of view. Spot average temperature distribution may represent temperature distribution in a single frame selected or summarized spot average temperature distribution for the collection of frames. The values of the spot average temperature may be displayed in a form of a graph representing spot average temperature values as a function of time of the scan.
Spot Standard Deviation, on the other hand, may be used to localize spots of increased temperature variation specific to the location of perforator vessels. Spot Standard Deviation includes calculation of the value of the standard deviation for the pixels included in the spot over the duration of the scan. Spot standard deviation represents the variation of the temperature distribution with reference to the average value of the temperature calculated for the time series of the duration of the scan. This algorithm represents the magnitude of temperature variations within a field of view during the scan. The values of spot standard deviation may be displayed in a form of a data matrix (frame). The values of spot standard deviation may be displayed in a gray scale mode or may be color coded according to the pseudo color palette. Spot standard deviation matrices may represent distribution of the magnitude of temperature variation with reference to the average temperature over the field of view. Spot standard deviation distribution may represent standard deviation distribution in a single frame selected or summarized spot standard deviation distribution for the collection of frames. The values of the spot standard deviation may be displayed in a form of a graph representing spot standard deviation values as a function of time of the scan.
Spot FFT may be used to localize spots of increased temperature modulation specific to the location of perforator vessels. Spot FFT calculates the frequency power spectrum distribution in the time series for each spot in the frames and the time series for each spot over the duration of the scan may be processed. Spot FFT represents the distribution of intensity of temperature modulation for the selected frequency ranges. Spot FFT temperature modulation intensities may be then displayed in a form of data matrix (frame). The values of spot FFT temperature modulation may be displayed in a gray scale mode or may be color coded according to the pseudo color palette. Spot FFT temperature modulation matrices may represent distribution of the magnitude of temperature modulation within selected frequency range over the field of view. Spot FFT temperature modulation distribution may represent temperature modulation distribution of a summarized spot FFT temperature modulation distribution for the collection of frames.
Combinations of indications by the above algorithms, in an embodiment, can be used to determine the location of perforator vessels on the tissue surface of examined area.
Once the scanned data have been processed, the results of the processed data may thereafter be presented as an image or images on the display screen of the imaging system 10. The image or images presented on the display screen, in one embodiment, may be pseudo-color or color images for evaluation. It should be appreciated that the image or images on the display screen may initially present areas of high power distribution at the locations of the perforators. Subsequently, for each algorithm employed, an operator may, if desired, manipulate the imaging system 10, including for example, selecting and narrowing different parameters, such as frequency and/or temperature range, to further enhance the contrast between, for instance, the perforator vessels (i.e., those vessels comprising the vascular architecture) and surrounding tissue to show the distribution and location of perforator vessels. The resulting processed image can be presented on the display screen, for instance, with areas of high contrast showing the distribution and locations of perforator vessels.
Thereafter, calibration of the image may be performed for translation purposes, i.e., positioning and aligning the image onto the corresponding location on the body of the patient. Specifically, the operator may perform software assisted dimensional calibration of the image either manually or automatically. To calibrate the image manually, the Dimensional Calibration Application, for example, may be initiated. In particular, the calibration marks on the ruler 100 may be identified and a line may be drawn between the calibration marks, which line serves to calibrate the image. To determine locations of perforator vessels within an image frame, a Grid Application may be employed, whereby a grid may be overlaid on the captured image on the display screen. The location of the origin of the grid (i.e., the origin of the coordinate system for the image frame) may be modified, including rotating the grid, if necessary, to subsequently align it on the patient's body.
Next, the origin of the grid may be moved to the mark on the patient's body and, in an example, the grid may be adjusted to align it with an edge of the ruler 100. The Measurement Application may then be initiated. In particular, a line from the origin of the grid may be generated toward the location of the perforators. The distances measured on the image from the lines, in one embodiment, may be the same as the distances on the patient body. Once the measurements have taken place, the measurements may be transferred from the image to the body of the patient, and the locations of the perforator vessels may be marked thereon.
Alternatively, automated calibration may be employed using feature identification software to avoid manual selection. It should be appreciated that the localization of the perforator vessels, in a preferred embodiment, may be carried out by the imaging system 10 with a resolution of approximately ±2 mm.
The dynamic imaging system 10 of the present invention may further be used pre-operatively, for instance, to stage the advancement of a disease and its effect on perfusion, such as in the case of diabetic neuropathy, or to plan a surgical procedure in response to the pre-operative result by identifying the best method and location for intervention. The imaging system 10 may also be used to evaluate perfusion in organs to be used during the transplantation, and may have applications in monitoring changes in perfusion related to patient behavior, such as exercise and diet, for instance, in the case of diabetic neuropathy. In such a situation, the imaging system 10 may provide important screening or diagnostic information, so as to identify the existence, stage the advancement, or monitor the effects of behavioral modifications, chemotherapy, surgical intervention or other medical or physical therapy over the lifetime of the patient.
The imaging system 10 may also be used in connection with post-operative evaluation, for instance, blood perfusion within a tissue graft or transplanted organ.
To perform a post-operative evaluation of, for example, a tissue flap subsequent to the transplantation, in one embodiment, the objective portion on the scanner (e.g., scanner 11 or 20) of system 10 may be placed adjacent the tissue graft so that blood perfusion during the post-operative period may be evaluated. As with the pre-operative evaluation, the area being evaluated need not be cooled down and may be maintained at substantially normal body temperature. Thereafter, operator may set parameters, for example, parameters similar to that in a Sequential Scanning Protocol. This protocol, in one embodiment, allows the taking of a series of images over an extended period of time (seconds, minutes, hours, days etc.). The number of image frames, the total period of image collection, and the pause between consecutive collections can be set. The analysis of the collected images allows instant evaluation of the blood perfusion during the postoperative period.
In the same way, and for similar reasons, the dynamic imaging system 10 of the present invention may be useful for post-operative monitoring of other surgical procedures including, but not limited to, rejoining of limbs following traumatic amputation, transplantation of organs or tissue, and interventional vascular procedures, such as angioplasty and stenting of vessels.
It should be noted that the design of the dynamic imaging system 10 and the methods of operating same provides ease of use and makes the system easily adaptable to various applications. For instance, the processor used in connection with the system 10 may be easily adapted for the particular application in use. Specifically, the type of application to be implemented can determine the type of algorithm that is to be used. For instance, whether the intention is to analyze massive changes of blood flow in major blood vessels, or minute changes in capillaries or cellular metabolic behavior, the system 10 can be easily adjusted and optimized by the user through an easy-to-use interface. Moreover, the configuration of the system 10 can lend itself to being used, for instance, in either a conventional wide-field surgery or alternately during minimally invasive surgery through the use of an endoscopic accessory lens. The design of system 10, depending on the tissue area under investigation can also allow the present system to be used outside of a sterile field.
While the invention has been described in connection with the specific embodiments thereof, it will be understood that it is capable of further modification. Furthermore, this application is intended to cover any variations, uses, or adaptations of the invention, including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains, and as fall within the scope of the appended claims. It should be noted that although surgical procedures are suggested, the potential uses for system 10 is not limited to such, or for that matter, medical applications.
The present application claims priority to U.S. application Ser. No. 60/585,806, filed Jul. 6, 2004, which application is hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60585806 | Jul 2004 | US |
